The objective of this study is to facilitate investigations into the genetic etiology of the epilepsies with emphasis on the spike-wave epilepsies and, in particular, petit mal absence. We propose to study the genetic transmission of these disorders through intensive studies of kindreds ascertained through a proband with a verified epileptic condition. The study utilizes two unique resources namely, (1) clinical records on 4,000 patients with a seizure disorder who were evaluated at the principal (and for a long time, only) neurological referral center in the Northwest during the period 1938 to 1963 and (2) EEG records on 8,000 individuals tested in the same period of time. Availability of these records permits the record linkage of clinical, laboratory (EEG) and genetic information. Probands will be selected from individuals evaluated in the Child Neurology Clinic (Epilepsy Center of Oregon), the Genetics Clinic (UOHSC) or in private practice and from individuals evaluated in the Neurological Clinic between the years 1938 and 1963. Systematic collection of clinical, genetic and laboratory (EEG) data will be extended to first, second and third degree relatives of probands. Special emphasis will be placed on record linkage of families to insure completeness and accuracy of pedigree and clinical information. The body of data thus generated will be the basis of more extensive family/genetic studies and be subjected to rigorous genetic analyses and tests of goodness of fit to various genetic models (hypotheses) using recently developed, statistically powerful, computer-adaptable methods.